Concentrically braced frames (CBFs) are stiff, strong, and were commonly used for seismic design in existing construction, but their inelastic seismic behavior is not easily evaluated, because it is dominated by tensile yield and post-buckling deformation. Recent research to better understand and evaluate CBF behavior for a range of construction eras is summarized. These results are combined with historic experimental results to develop fragility curves, which can be used to estimate seismic performance and to evaluate repair and retrofit strategies. Evaluation of seismic performance also requires analytical models to predict deformation demands due to seismic excitations, but current models provide limited accuracy. Recent developments in modeling and analyzing CBF performance and seismic demands and improved prediction methods are presented. The seismic performance of CBFs is strongly dependent upon the gusset plate connection design and performance as well as brace cross-section and configuration, and these details have a major impact on the seismic damage expected from a given CBF system.
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